The invention relates to the construction of buildings and in particular to the construction of buildings employing steel framing for various components of the building. More specifically the invention relates to a metal joist for supporting roofs, floors, ceilings and decks.
Without limiting the scope of the invention, its background is described in connection with reference to the construction of buildings and in particular the construction of buildings employing steel framing for various components of the building.
In the past, a number of joist systems have been designed and fabricated for use in building construction. Typically, such joists have been used as floor, roof and deck supports. The design and fabrication of such joists have largely been on an application-by-application or building-by-building basis. Additionally, the fabrication of such joist systems has been complicated due to constraints imposed by the particular design of the joist components and the fastening system used to connect the joist components.
Thus, there exists a need for a simplified joist systems and design wherein components can be more standardized while still meeting the requirements of difference building designs.
In one embodiment of the invention, a building includes a metal roof and joist system. As used herein the term xe2x80x9cmetal buildingxe2x80x9d refers to a structure having a frame composed primarily of metal members, including the joist of the invention. The joist system includes upper and lower longitudinally extending chords 12, 24, having substantially identical cross-sectional geometry. The upper and lower chords are substantially parallel and a plurality of web members 30 are interposed between the parallel chords. Each of the chords 12, 24 is comprised of an upper chord segment 14, opposed parallel side walls 16, and inwardly extending lower chord segments 18, with the lower chord segments being parallel to the upper chord segment. A pair of flanges 20 extend downwardly from the innermost edge of each of the inwardly extending lower chord segments 18 of the chord. The flanges 20 define a longitudinally extending continuous web receiving aperture 22 traversing the length of the chord. Preferably, these chord members are integrally formed from a single steel sheet or plate.
Each of the web members is formed from an upper web segment 32, opposed parallel side walls 34 extending perpendicularly from the upper web segment, and inwardly extending lower web segment 36. The innermost edges of the inwardly extending lower web segments 36 define a longitudinally extending slot 38. Preferably, the upper web segment, parallel side walls, inwardly extending lower web segments 36 are also integrally formed from a single steel sheet or plate. Each of the web members has first and second ends received in the web receiving apertures 22 of the chords. The web members 30 are secured to the upper and lower chords by welding, or with mechanical means selected from a group consisting of screws, bolts, and rivets and combinations thereof. In practice, the web receiving apertures of the upper and lower chords are positioned in opposed parallel relationship and the width of the web receiving aperture 22 is equal to the width of the upper web segment 32 of each of the web members so that the web members abut the flanges of each of the chords when the joist is fabricated.
A saddle is provided for receiving and positioning the ends of the joists on a horizontal structure such as a wall, or on a floor, deck or roof frame. The saddles include an upper saddle member, opposed parallel side members and outwardly extending bearing plates, the outwardly extending bearing plates being parallel to the upper saddle member. The saddle is received or seated in the upper chord of the joist to position and support the joist.
The joists and system of the invention are simple yet elegant in design, requiring a minimum of stock materials. The joists may be quickly and easily fabricated, reducing overhead and labor costs typically associated with the fabrication of structural members. The open construction of the chords and web members allows for variations in material dimensions which might otherwise impede or slow fabrication. If desired, due to the design of the joists of the invention, the joists may be quickly and easily fabricated on site from precut sections.